连续相位QPSK调制的简化接收机

Simplified receiver for continuous phase QPSK modulation

针对连续相位QPSK(Continous Phase QPSK,CPQPSK)调制传统最佳接收机复杂度随整形脉冲长度呈指数增长问题,提出了基于劳伦特分解的简化接收机.通过将劳伦特分解应用到CPQPSK方案,推导出了CPQPSK信号PAM叠加的形式,得出了基于劳伦特分解的全响应CPQPSK最佳接收机.根据PAM信号被调制脉冲的特点,当仅选用其中部分滤波器,得到了降低复杂度的全响应CPQPSK接收机,并对接收机的性能进行了计算机仿真.仿真结果表明在信噪比较高的情况下,仅用3个匹配滤波器的简化接收机就可以达到用8个匹配滤波器的最佳接收机的性能.

The complexity of the conventional optimum receiver for continuous phase QPSK （CPQPSK） increases exponentially with the length of the shaped frequency pulse. A simplified receiver based Laurent decomposition （LD） for CPQPSK is proposed. CPQPSK signals can also be decomposed according to the LD theory. The optimum receiver and the simplified one for full response CPQPSK signals are designed based on LD. The latter is achieved by choosing several key filters in the matched filter bank for the optimum receiver. Computer simulations are performed on these simplified receivers. Simulation results show that the bit error rate performance of the simplified receiver with three matched filters can approach that of the optimum receiver with eight filters under a higher signal-to-noise ratio.